#define  _CRT_SECURE_NO_WARNINGS
#include <stdio.h>

int main()
{
	int m = 0;
	int t = 0;
	int s = 0;
	scanf("%d%d%d", &m, &t, &s);
	if (t == 0)
		printf("0\n");
	else
	{
		int n = (m * t - s) / t;
		if (n >= 0)
			printf("%d\n", n);
		else
			printf("0\n");
	}
	return 0;
}
